The invention is directed to a device for coating traveling material webs, and more specifically, the invention is directed at such device having a pressurized coating space formed between a doctor element, a counter roll carrying a material web and a discharge opening of a chamber for the coating mixture wherein a guide device is arranged in the coating space with the coating material flowing around the guide device.
A coating device for coating a traveling material web is shown in DT-PS 95 770. With such a coating device, the coating mixture proceeds from a chamber in which it is first held as in a reservoir through a slot or gap type outlet opening of the chamber into a coating space in which the coating mixture continues to be held under pressure. The coating space is formed on the material web and/or the counter roll carrying it and is defined relative to these by a front regulating plate, the mouth of the chamber outlet opening, and by the doctor element. In the process, the coating mixture can discharge from the coating space against the direction of travel of the web through a choking gap formed between a front regulating plate and the counter roll and/or the material web. This generally prevents air from being introduced into the coating space through the material web.
Air inclusions in the coating have the disadvantage of producing a nonuniform coating such as a coating that includes striations. But a striated appearance of the coating is caused not only by air inclusions, but also, for example, by pulsations in the coating mixture flow or by stagnant or swirling boundary layers.